Sleeve with insert for repairing high-pressure fluid pipes

ABSTRACT

A sleeve f or repairing a fluid pipe ( 12 ), including a rigid or flexible shell ( 22 ) which forms a mold that surrounds at least one defective area ( 10 ) of the pipe. A liquid-state polymerizable material is injected into the mold, which polymerizes and seals the defective area. The sleeve also includes an insert which is made up of several coils of a filiform element ( 14 ), which is wound into a helix around the defective area of the pipe, before the polymerizable material is injected or infused.

TECHNICAL FIELD

This invention concerns the systems used for repairing pipes designed tocarry high-pressure fluids such as pipelines for transporting petrol andrelates particularly to a sleeve with insert for repairing high-pressurefluid pipes.

BACKGROUND

Generally speaking, a sleeve employed as an injection mould is used toseal a leak in fluid pipes. The portion to be repaired is encased by thesleeve, which forms a watertight cavity in which a polymerizable liquidmaterial is injected. As it polymerizes, this liquid forms a coatingthat seals leaks and provides insulation against heat, chemicals andshocks.

Sleeves that can be used in this technique are described, for example,in the following patents: FR 2.158.895, EP 278.050, U.S. Pat. No.4,610,740, or GB 2.119.884. They are made up of two cylindricalhalf-shells joined together to form a single shell covering the portionto be protected or repaired. The polymerizable liquid material(generally made of components of an epoxy resin or polyurethane resin)is then poured through an injection hole provided in the wall of theshell, into the cavity thus created.

These sleeves formed by two half-shells are thus adapted for pipes of agiven diameter. Sleeves of different diameters must therefore beavailable to fit the various pipe diameters. This leads to the necessityof having different moulds to be able to manufacture half-shells havingdiameters adapted to all pipes, and thus results in a very high cost.

An attempt was thus made to use a modular sleeve as described in thepatent EP 0.856.117 made up of identical moulds and thus requiring onlyone mould for manufacturing modules. In this technique, by varying thenumber of modules making up the sleeve, the latter can be adapted topipes of different diameters. In addition, each module includes a maleand female portion so that the male portion of a module can fitpartially or completely into a female portion of the adjoining module.This allows a sleeve consisting of a fixed number of modules to beadapted to pipes whose diameters are between a minimum value and amaximum value. Unfortunately, due to its modular structure, this type ofsleeve does not withstand very high pressures of the order of a fewdozen bars to which are subjected certain pipes designed to carry fluidsover long distances as is the case with petroleum pipelines.

With the aim of carrying out repairs on high-pressure pipelines, thepatent U.S. Pat. No. 5,632,307 describes a device that consists of anelastic band in the form of a coil with multiple windings as on a clockspring that is placed around the pipeline at the defective area. Inaddition to the fact that the corroded area must be plugged, that therigid band is difficult to install due to the spring effect, and finallythat installing it requires a significant embankment under the pipelineto be able to wind the various layers of the coil, such a device cannotbe used if the pipeline is oval, if it is highly bent at the defectivearea or if, additionally, it is necessary to grind the weld beads, ifany, at this location so that the device can operate efficiently.

SUMMARY OF THE INVENTION

This is why the purpose of the invention is to provide a sleeve designedfor repairing high-pressure fluid pipes.

Another purpose of the invention is to provide a sleeve designed forrepairing pipes with a defective area, whatever the geometry of thepipeline or its bending radius at the location of the defective area.

The purpose of the invention is thus a sleeve for repairing fluid pipesconsisting of a rigid or flexible shell acting as a mould to encase atleast one defective area of the pipe and in which is injected aliquid-state polymerizable material that seals the defective area as itspolymerizes. The sleeve also includes an insert made up of a pluralityof turns of a thread-like element wound in a spiral around the pipe atthe location of the defective area prior to the injection or infusion ofthe polymerizing material.

BRIEF DESCRIPTION OF THE DRAWINGS

The purposes, objects and characteristics of the invention will becomemore apparent from the following description when taken in conjunctionwith the accompanying drawings in which:

FIG. 1 represents a portion of pipeline consisting of a defective areaon which an insert has been wound according to the principles of theinvention and;

FIG. 2 represents a section of the sleeve placed around the pipeline atthe location of the defective area and showing the different strands ofthe insert above the defective area.

DETAILED DESCRIPTION OF THE INVENTION

Traditionally, a sleeve made up of a rigid or flexible closed shell inwhich a polymerizable material such as polyurethane or epoxy resin isinjected or infused (injected by vacuum suction), is placed all aroundthe pipeline so that the defective area is covered. Such a defectivearea illustrated by the dotted areas in FIG. 1 can result from corrosionof the pipeline 12 that creates a weak spot at the location where thereis a reduction in the thickness of the pipeline that could be piercedunder the effect of the pressure of the fluid to be carried by thepipes.

When a sleeve is installed according to the invention, a bonding andanti-corrosive material is first placed on the defective area. Then, inaccordance with the invention, an insert 14 is wound and centered aroundthe pipe so that it completely covers the defective area 10 as well asthe two parts of the pipe that are not defective adjacent to thedefective area.

The insert is wound helically around the pipe with a pitch that leaves asufficient space 16 between two adjacent turns of the insert. Thus, byusing a 10 mm-wide insert, a space of 1 mm can be left. This space isnecessary so that the resin injected or infused into the rigid orflexible shell of the sleeve can coat the turns of the insert and adhereto the surface of the pipe wall.

When the thread-like element constituting the turns of the insert hasbeen wound around the pipe, each of the ends of the element is fixed tothe turn by a clamp 18 or 20.

The rigid or flexible shell 22 of the sleeve is then placed around thepipe as shown in FIG. 2. This rigid or flexible shell 22 must cover allturns of the insert placed beforehand around the pipe and must havesufficient height so that there is enough gap to inject or infusepolymerizable material into it. In this manner, with a 10 mm thickinsert, the shell will have a height of 20 mm.

In case of infusion, the vacuum created beforehand with the help of avacuum pump enables the flexible shell to plate and contour the supportalready in place. The resin can then be infused; this will ensure thatthe area to be repaired is completely filled by the polymerizablematerial.

When the rigid or flexible shell 22 has been fixed on the pipe so thatit is hermetically closed, the polymerizable material in the liquidstate is injected or infused inside the rigid or flexible shell througha port 24 using a vacuum pump. The quantity to be injected or infusedcorresponds to the filling of the shell, the polymerizable materialcompletely covering all the turns of the insert and filling the gapsbetween turns.

It should be noted that the defective area 10, generally caused bycorrosion, has a thickness that is clearly less than the normalthickness of the pipe wall, as shown in FIG. 2. The pipes therefore havea hollow at the location of the zone and as a result, the insert is notalways in contact with the wall of the pipe at this location. This isnot important so long as the resin resulting from the polymerization ofthe polymerizable material injected or infused completely covers theturns of the insert and acts as a transmitter of forces between the pipewall and the insert.

The insert used in the sleeve according to the invention is athread-like flexible element (rope), a semi-rigid element (metal braid),or a preformed element (composite spring type) suitable for being woundaround the pipes. It can have a section of any shape that may bevariable along the insert, but it is preferable that the insert has acircular and constant section. It may be made of any material that hasgood tensile strength such as aramid fiber (Kevlar® for example) and inparticular it may be made of natural fibers (glass or carbon forexample), synthetic fibers or prepregged fibers. The thickness of theinsert or its diameter, if it is a circular section element, depends onits mechanical characteristics. It can vary from a few mm (2 mm forexample), to dozens of mm (50 mm for example).

The purpose of the insert is to neutralize the radial forces that areapplied on the wall of the pipe at the location of a defective area bytransforming these radial forces into tractive forces distributed overeach of the turns of the insert on the defective area. The radial forcesexerted on the pipe walls are transmitted to the insert by the resinthat fills the rigid or flexible shell and which is solid afterpolymerization of the polymerizable material injected or infused intothe shell that plays the role of a casing here. The combination of theinsert and the resin is equivalent to a composite material in which theeffectiveness of the assembly to counter the radial forces being appliedon the pipe walls results from the synergy between the two components.

The sleeve according to the invention may be used with pipes of alldiameters ranging from 100 mm to several meters. Its width may beadapted according to the pipe, for example from 300 to several meters(limit associated with the technology of thermoplastics or infusion) andits height is preferably between 10 mm and 80 mm.

It may be used for repairing pipes whose walls are corroded to up to 80%of their thickness, whatever the width of the defective area. Thus, anarea of 200 mm axial length, 300 mm peripheral width and having a depthof 5.70 mm i.e. 80% of the wall thickness (7.1 mm) of a pipe with adiameter of 324 mm has been successfully repaired.

A key feature of the sleeve according to the invention, resulting fromits very structure, is its adaptability to pipes of any shape. Thus, itcan be installed even when the pipes are not circular but rather oval,whatever the bending radius of the pipe (on a bend for example) and evenwhen the pipe has an axial or peripheral weld, as it is not necessaryfor the insert to be in contact with the pipe wall.

The sleeve according to the invention may be used for repairing anytubular structure damaged due to reduction in thickness caused bycorrosion or cracking, in order to restore its mechanicalcharacteristics. It may be used by maintenance companies, fluidtransportation maintenance companies (mainly hydrocarbons) though itsuse is not limited to this field. In this manner, because of itsmechanical characteristics, it may be used in the building and civilengineering sector, particularly for reinforcing columns and othersupporting pillars.

1. A sleeve for repairing a fluid pipe having a defective area wherethere is a reduction in the thickness of the pipe, said sleeveconsisting of a rigid or flexible shell adapted to act as a mold toencase at least said defective area and in which can be injected orinfused a liquid-state polymerizable material that is adapted to sealthe defective area when it polymerizes, and an insert made up of aplurality of turns of a thread-like element wound in a spiral aroundsaid pipe at the location of said defective area prior to the injectionor infusion of said polymerizable material, wherein a pitch between twoadjacent turns of said insert is constant and small with respect to thewidth of said insert and defines a space between adjacent turns of saidinsert such that said polymerizable material can coat said turns andadhere to the surface of the pipe wall, and wherein said sleeve isadapted to form a hermetic seal enclosing all the turns of saidthread-like element.
 2. A sleeve according to claim 1, wherein saidpitch is about 1 mm and said turns have a width of about 10 mm so thatsaid polymerizable material covers each of said turns during injectionor infusion into said rigid or flexible shell.
 3. A sleeve according toclaim 2, in which said thread-like element is a flexible element ofconstant circular section formed of natural, synthetic or prepreggedfibers.
 4. A sleeve according to claim 3, in which said thread-likeelement is made up of aramid fibers.
 5. The sleeve of claim 1, wherein aratio between the pitch and the width of the insert is 1:10.
 6. A sleevefor repairing a fluid pipe having a defective area where there is areduction in the thickness of the pipe, said sleeve consisting of arigid or flexible shell adapted to act as a mold to encase at least saiddefective area and in which can be injected or infused a liquid-statepolymerizable material that is adapted to seal the defective area whenit polymerizes, and an insert made up of a plurality of turns of athread-like element wound in a spiral around said pipe at the locationof said defective area prior to the injection or infusion of saidpolymerizable material, wherein a pitch between two adjacent turns ofsaid insert is constant and small with respect to the width of saidinsert and defines a space between adjacent turns of said insert suchthat said polymerizable material can coat said turns and adhere to thesurface of the pipe wall, wherein said sleeve is adapted to form ahermetic seal enclosing all the turns of said thread-like element, andwherein each of the ends of said thread-like element is fixed to theadjacent turn by a clamp.
 7. A process for repairing a fluid pipe with adefective area consisting of winding a thread-like element in a spiralaround the pipe at the location of said defective area, surrounding theportion of the pipe where said defective area is situated by ahermetically closed rigid or flexible shell, said rigid or flexibleshell being adapted to completely cover the turns of said thread-likeelement and injecting or infusing in said shell a polymerizable liquidmaterial designed to form a resin after polymerization, wherein a pitchbetween two adjacent turns of said insert is constant and small withrespect to the width of said insert and defines a space between adjacentturns of said insert such that said polymerizable material can coat saidturns and adhere to the surface of the pipe wall.
 8. The process ofclaim 7, wherein a ratio between the pitch and the width of the insertis 1:10.